Fix extra komma

board/board.go

@@ -61,10 +61,12 @@ func (b *Board) WriteJSON(w io.Writer, startCol, startRow, cols, rows int) {
 
 	for y := startRow; y < sr+rows; y++ {
 		for x := startCol; x < sc+cols; x++ {
+			if (x != startCol) { 
+				w.Write([]byte{','})
+			}
 			t := &jsonTile{x, y, b.Get(x, y).Name(), ""}
 			bs, _ := json.Marshal(t)
 			w.Write(bs)
-			w.Write([]byte{','})
 		}
 	}